1. Field of the Invention
This invention relates to improvements in apparatus for feeding perforation sealer balls or the like into a stream of well treating fluid being pumped through a fluid flow line into an oil or gas well. The apparatus of the invention may also be used for introducing other elements, such as pipe cleaning pigs, into fluid flowing at high pressure through a liquid flow pipe.
2. Description of the Prior Art
U.S. Pat. No. 2,754,910 to Derrick and Kaltenberger discloses a method and apparatus for temporarily and selectively closing some of the perforations in oil well casing so that treating fluid may be forced under pressure through other of the perforations and into the surrounding earth formation. In performing the method, perforation sealer elements, such as sealer balls, are introduced into the stream of treating fluid being pumped down the well. The sealer balls commonly have a metallic core surrounded by a coating of rubber or the like, and are adapted to become seated in those perforations taking fluid flow at the higher velocities to block the flow of fluid through those perforations and to permit flow through other, unblocked perforations.
In fracturing or acidizing operations, for example, the treating fluid is pumped into the well under high pressure, which may range from a few hundred psi to 15,000 psi or even higher. Thus, one of the problems involved is to overcome the high pressure of the fluid into which the sealer balls are injected.
Moreover, the size of the perforations to be sealed will vary depending upon the perforating equipment used to make them. Thus, in the practice of the perforation sealing process of the foregoing Derrick and Kaltenberger patent, the sealer balls that are injected into the fluid stream must be of the proper size to close the particular perforations encountered.